Cobalt phosphate-based organic–inorganic hybrid nanobelts were successfully synthesized in the presence of trioctylamine (TOA) via a solvothermal system. The inorganic cobalt phosphate layers and organic n-octylamine layers in this structure arranged alternately, both of which were parallel to the axial direction of the nanobelts, and the layered distance is 4.0 nm. The formation of this nanostructure proceeds via two reactions. Trioctylamine molecules undergo C–N bond cleavage to form octylaminevia the redox reaction between the Co(III) and trioctylamine. Octylamine was protonated to incorporate into the inorganic framework, resulting in the formation of organic–inorganic hybrid nanobelts. In addition, the as-synthesized nanobelts show excellent removal ability for the trace heavy metal ion Pb²⁺ in wastewater.